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  • 1985-1989  (2)
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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish diseases 8 (1985), S. 0 
    ISSN: 1365-2761
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Efficacy of specific antibody on serum resistance and adhesion was investigated using a pathogenic strain of Aeromonas salmonicida A-7301 (which was autoagglutinative, haemagglutinative and protease production positive), a protease-deficient, non-pathogenic mutant NTG-1 induced from A-7301 (autoagglutinative and haemagglutinative), and a non-pathogenic strain GH-7501 (non-agglutinative, non-haemagglutinative and protease positive). A-7301 could grow and produce protease extracellularly in the presence of rainbow trout anti-A-7301 serum, resulting in a considerable reduction of the antibody titre. NTG-1 similarly grew, but the titre scarcely decreased. GH-7501 could not survive in this medium. A-7301 and NTG-1 possessed a high capacity to adhere to the surface of fish monolayer cell cultures, whereas GH-7501 lacked the capacity. The capacity for adhesion was not inhibited by the antibody. Although live NTG-1 cells were ineffective as a live vaccine, sockeye salmon receiving protease fraction (obtained from extracellular products of A-7301 by DEAE-cellulose column chromatography) inactivated with normal serum, suffered only a low mortality when challenged with A-7301. Thus, although the antibody specific to autoagglutinating cells showed no effects on serum resistance and adhesion, which are involved in the infectivity of this pathogen, the possibility of protease as an effective protective antigen was demonstrated.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish diseases 10 (1987), S. 0 
    ISSN: 1365-2761
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Abstract. The transformation of Aeromonas salmonicida with DNA fragments from bacterial cell-free sonicates was investigated with intraspecific, interspecific band intergeneric fish pathogenic bacteria including Aeromonas salmonicida, Aeromonas hydrophila, Pseiidomonas fluorescens and Vibrio anguillarum strains as donor bacteria. A phenotypic marker for transformation was extracellular protease production since a protease-deficient mutant NTG-1 induced from pathogenic A. salmonicida strain A-7301 by mutagenesis was used as a recipient. This mutant was non-pathogenic to rainbow trout. The mutant was incubated with each sonicate at 20°C for 20 days with a nutrient-poor medium containing a trace (5 μg/ml each) of both humic acid and tryptone in the presence of clean river sand (100 g/100 ml medium) corresponding with an environment of rivers. During the incubation, the survival of mutant NTG-1 cells was observed and protease positive NTG-1 cells were isolated from each culture. The protease production of the isolates was due to the transmission of protease genes of the donor strains. The activity of proteases produced by the transformants extra-cellularly was determined. These transformants induced with the sonicates of the parent strain, intraspecific strain and with the sonicates of the interspecific A. hydrophila strain were pathogenic to rainbow trout, whereas the transformants derived with the sonicates of the intergeneric strains P. fluorescens and V. anguiUarum showed non-pathogenicity, although all the donor strains, with the exception of the P. fluorescens strain, were pathogenic. These findings are interesting since they demonstrate that trausformation in A. salmonicida occurs with considerable ease even intergenencally and interspecifically, as well as intraspecifically in river environments, and that there is a large difference in the lethal toxicity of extracellular protease produced by these bacteria.
    Type of Medium: Electronic Resource
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